DDT & Obesity: New science on harms of old pesticide

Plenty of calcium, fruits, vegetables & exercise. No drinking, no smoking, cut down on caffeine. Oh, and avoid DDT breakdown products — they may put your soon-to-be-born baby on the road to obesity.

Researchers in Spain say they were surprised to find this link between DDT and overweight infants. Turns out when women of normal weight have higher levels of DDE (DDT’s breakdown product) in their blood during pregnancy, their babies are twice as likely to grow quickly during the first 6 months of life, and 4 times as likely to be overweight when they reach the 14-month mark.

No one quite understands why — are the babies less active? eating more? — but there are plenty of animal studies suggesting an answer: some pollutants (at very low levels) interfere with normal hormone functions to slow the metabolism and cause obesity.

“… a growing body of data has been indicating that some pollutants — known colloquially as obesogens — can trigger the body to put on the pounds. In animals, these pollutants will sometimes lead a mouse to become rotund despite eating no more and exercising no less than its lean cousins.”

It should be easy to avoid contact with DDT though, right? After all, it’s been banned in the U.S. for nearly 40 years, and use has been pretty much phased out around the world. (In some countries, small quantities of DDT are still used for malaria control — though the World Health Organization is working hard to help put safer tools in place.)

So how is it that 99%* of us carry DDT breakdown products in our blood? The short answer: DDT and DDE hang around for decades.

Women who were exposed as children back when DDT was used may have passed the chemical on to their children during pregnancy and breastfeeding. Root crops such as carrots and potatoes can pull DDE from the soil for years after the parent chemical was applied. And these long lasting pesticides can travel the globe for years after use, stopping along the way as they travel to the polar regions, where contamination levels can be astonishing.

On top of all that, Canadian scientists are now saying that climate change may increase our exposure to legacy chemicals like DDT. As global temperatures rise, lingering pollutants are likely to be released from frozen water and soil where they’ve been trapped, putting them back into circulation for another round of contamination.

Since obesity is just one more in a long list of known ways DDT (and other persistent chemicals) can damage human health, this is disturbing news for us all — whether we're expecting mothers or no.

*DDT breakdown products were found in the blood of 99% of the people tested by CDC.